The present invention is directed, in general, toward test apparatus and, more particularly, toward apparatus for determining the presence of an analyte in a sample.
Recently, various methods have been developed for detecting a variety of analytes in samples where the analyte is capable of reacting with a reagent to produce a particular color or hue. The color which is produced can, in turn, be detected as, for example, by using a spectrophotometric instrument. These prior devices typically are complicated and involve electronic components and do not allow for the variation in testing conditions. More particularly, many devices are known which match the colors of an unknown test sample in serial dilution with those of known concentrations of an authentic standard.
Some of the techniques which have become increasingly useful in detecting an analyte in a sample use antibodies. In these techniques the antibody is used to detect the presence of the analyte, in this case an antigen, for which the antibody is specific. Over the last several years, the sensitivity of antibody-based tests have increased such that less liquid volume is required enabling the use of the microtiter plates.